Beds of the type used in health care facilities and sometimes in home care settings include a longitudinally segmented or sectioned bed frame and a mattress supported on the frame. Typical bed frame sections include an upper body or torso section corresponding approximately to an occupant's torso, a seat section corresponding approximately to the occupant's buttocks, a thigh section corresponding approximately to the occupant's thighs, and a calf section corresponding approximately to the occupant's calves and feet. The seat, thigh and calf sections may be referred to collectively as a lower body section; the thigh and calf sections may be referred to collectively as a leg section. The upper body section is orientation adjustable from a substantially horizontal orientation to a more vertical orientation, typically about 65° or 70° relative to horizontal. The thigh and foot sections are also orientation adjustable in opposite rotational senses so that the mutually proximate ends of those sections define an elevated apex. The adjustability of the upper body, thigh and calf sections allow a user to control the contour or profile of the frame. Portions of the mattress that overlie the upper body, seat, thigh and calf sections of the frame are designated as mattress upper body, seat, thigh and calf sections. The mattress is affixed to the frame so that its contour conforms to that of the frame.
The adjustability of the various frame sections and the conformability of the mattress can contribute to occupant comfort. For example it is not uncommon for the upper body section to be at an orientation of up to about 65° or 70° relative to horizontal and for the thigh and calf sections to be oriented so that the mattress fully supports the occupant's legs when the occupant is supine with his or her legs bent at the knees. The adjustability can also help mitigate the inherent tendency of the upper body section to push the occupant toward the foot of the bed when the upper body section undergoes a change in orientation from a more horizontal orientation to a less horizontal (i.e. more vertical) orientation. For example, as the upper body section is rotated upwardly (further away from horizontal), the thigh and calf sections can be concurrently rotated from horizontal to non-horizontal. The rotation of the thigh section places it at an inclination that causes the corresponding mattress section to resist the tendency of the upper body section to push the occupant footwardly.
Some bed frames may not feature the full spectrum of adjustability described above. For example, some frames may have an adjustable upper body section as described, but not adjustable thigh and calf sections. As a result, the bed is unable to counteract the tendency of the upper body section to push the occupant footwardly. Consequently, it may be necessary for a caregiver to reposition the occupant. The repositioning diverts the caregiver's time from other tasks and involves risk of injury to the caregiver. Moreover, involuntary occupant migration along the mattress can impart shear stress and stretch to the occupant's skin and soft tissue, resulting in risk of skin injury.
Accordingly, it is desirable to provide a mattress able to compensate for lack of adjustability of the frame, particularly a lack of orientation adjustability in the lower body section.